Hydrogen peroxide &lpar;H2O2&rpar; is the simplest peroxide &lpar;a compound with an oxygen-oxygen single bond&rpar;&period; It is also a strong oxidizer&period; Hydrogen peroxide is a clear liquid&comma; slightly more viscous than water&period; In dilute solution&comma; it appears colorless&period; Due to its oxidizing properties&comma; hydrogen peroxide is often used as a bleach or cleaning agent&period; The oxidizing capacity of hydrogen peroxide is so strong that it is considered a highly reactive oxygen species&period; Hydrogen peroxide is therefore used as a propellant in rocketry&period; Organisms also naturally produce hydrogen peroxide as a by-product of oxidative metabolism&period; Consequently&comma; nearly all living things &lpar;specifically&comma; all obligate and facultative aerobes&rpar; possess enzymes known as catalase peroxidases&comma; which harmlessly and catalytically decompose low concentrations of hydrogen peroxide to water and oxygen